Pencilfish (Nannostomus species) is a intermediate-level freshwater fish that needs at least 10 gallons and 72-82°F. Slender, shy fish with a bold stripe, best in a planted tank with dim light.

Care facts at a glance

Scientific nameNannostomus species
FamilyLebiasinidae
OriginSouth America
Adult size2 in
Minimum tank10 gallons
Temperature72-82°F
pH5.5-7.0
TemperamentPeaceful, shy
Social behaviorSchooling, keep 6+
Swim levelUpper to mid
DifficultyIntermediate
DietMicro pellets, frozen foods, baby brine shrimp
Typical lifespan3-5 years

Quick tips

  • Keep a group of six or more.
  • Use a tight lid.

San Diego water

Prefers softer, more acidic water than San Diego's tap (pH roughly 7.6-8.6, hard). Most keepers blend tap with RO/DI water or use a remineralized RO/DI supply. Learn the numbers in our San Diego tap water guide.

Before you buy

Make sure your tank is cycled (how to cycle a tank), check your numbers with the water testing guide, and use the compatibility guide to check tankmates. These are general ranges; individual fish and local water vary.

Find it at Pet Zone

Pet Zone Tropical Fish is a San Diego aquarium store with two locations. Stock changes daily, so call ahead if you are after a specific species or plant. Shop online at petzonesd.com.

Pet Zone Convoy

4160 Convoy St, San Diego, CA 92111
(858) 987-0309
Open daily, 10am-6pm

Aquascaping, planted tanks

Pet Zone Mid-City

4266 University Ave, San Diego, CA 92105
(619) 283-1812
Closed Monday; Tue-Fri 10:30am-6pm, Sat 11am-6pm, Sun 11am-4pm

Monster fish, koi